| abstract |
In one embodiment of the present invention, a virtual-machine monitor detects entry and exit from guest-operating system code, storing the values of a set of high-order floating point registers in memory on entry, and restoring the values of the set of high-order floating point registers on exit. The virtual-machine monitor can then use the set of high-order floating point registers as scratch registers for emulation of guest-operating-system instructions. In alternative embodiments of the present invention, a virtual-machine monitor obtains scratch registers for any code that the virtual-machine monitor can detect entry into and exit from, and for which a set of infrequently used registers can be identified, by storing the current contents of the set of registers upon detected entry into the code and restoring the original contents of the set of registers upon exit from the code, emulating access to the set of registers in the code by memory-access operations. |